I hope not. I worry about this because both of my parents were diagnosed with Alzheimer's. Not sure whether there's a genetic propensity, but I really can't do anything about it, so I try not to think about it.
Come, grow old with me. the best is yet to be..... I used to be afraid of it. Now that I've arrived, I find that while it has special challenges, it's not as intimidating as I once thought. Even though you slow down considerably, there are built in compensations. One is that you are given the ability to accept your circumstances and enjoy living in different, less strenuous ways.
Millennials are the most ageist group ever. They'll stick up for every other social segment, but spit on "the old" because they don't participate on SnapChat. That is my fear. Being a BIGGER nothing because I don't download an app.
One of the main reasons I put so much effort into keeping myself in tip-top physical shape is that it also helps alleviate many of the naturally-occurring potential maladies associated with getting older. My body doesn't respond equally as it did when I was younger, but at the same time, I don't suffer "old man" syndrome like many men my age. I don't feel "old", meaning that my mindset and outlook haven't switched drastically from when I was in my 20s or 30s.
Mentally, my concern is cognitive issues. My memory started playing nasty tricks on me at age 28, and my maternal grandfather had serious problems with his around age 65 or 70. He lived until age 80-something, but his last decades were difficult.